n3 咪唑 此啶 (imidazole) (pyridine) H 2 8 H 嘌呤 吲哚( indole) (purine咪唑 (imidazole) H N N 1 3 N 吡啶 (pyridine) 吲哚(indole) N H 1 2 3 4 5 6 7 9 8 7 6 5 4 3 2 1 H N N N N 嘌呤 (purine)